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Maintenance
11) Inspection of Compression Pressure
1.
Start the engine to warm up for 5 minutes, then stop
the engine.
2.
Shift gear into neutral (N).
Remove lock plate 1 (of stop switch lanyard) from
3.
stop switch.
Remove lock plate (of stop switch lanyard)
f r o m s t o p s w i t c h b e f o r e m e a s u r i n g
compression pressure. This will prevent
engine from accidental starting.
4.
Remove plug cap and then spark plug.
Clean areas around spark plug on the
cylinder before removing spark plug to
prevent dirt from entering cylinder.
Install the compression gauge 2 to plug hole.
5.
Compression Gauge 2 :
P/N. 3AC-99030-0
6.
Fully open throttle, crank the engine until compression
gauge 2
compression pressure.
Compression Pressure (Reference) :500 min
With decompressor operate :
0.34 MPa (49.3 psi) [3.5 kgf/cm
Without decompressor operate :
0.93 MPa (137.8 psi) [9.5 kgf/cm
(*Remove Exhaust rocker arm)
· Compression pressure is affected much by
c r a n k i n g s p e e d , a n d n o r m a l l y c h a n g e s
approximately 10 – 20 %.
· Do not pull choke knob when measuring
compression pressure.
7.
If compression pressure is below specified value, put
small amount of engine oil into cylinder, and perform the
test again.
· If compression pressure increases after the
above measure, check piston and piston rings
for wear. Replace if necessary.
· If compression pressure does not increase
a f t e r t h e a b o v e m e a s u r e , c h e c k v a l v e
clearances, valves, valve seats and cylinder
head. Adjust or replace if necessary.
3-12
CAUTION
CAUTION
-1
]
2
]
2
(rpm)
1
2
4st 4/5/6 2020
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